Determination Of Nitrofuran Metabolites And Beta Adrenergic Agonists Residues In Poark Tissue By LC-MS-MS

The veterinary drug residue in food has become a weighty and disputed problem in recent years and it is extremely necessary and urgent to develop convenient and high-efficient previous treatment method, and the high sensitivity and alternative detection method. Through comparation between detection methods of clenbuterol and ractopamine by LC-MS and MS-MS, including detection limits and linear scale, way of clenbuterol and ractopamine detection were set up. Studying on parameter of LC-MS resulted in optimized detection conditions. Besides, Recovery rate and precision of measurement in detecting clenbuterol and ractopamine in pork were studied. As regard to detection of nitrofuran metrabolites , by comparing different extraction methods and choosing extraction solvent pre-treatment methods were set up. On the base of optimized MS-MS parameters, repeatability and recovery rate of the method was studied. The results were described as follows.(1)A high performance liquid chromatography-tandem mass spectrometric method was established for simultaneous determination of the nitrofuran metabolites. The nitrofuran metabolites were released in HCL solution and derivatised with 2-nitrobenzaldehyde(2-NBA) overnight at 37℃.After adjusting PH range from 7.0 to 7.5. Then the analytes were extracted by ethyl acetate identification was achieved by electrospray ionization in positive mode(ESI+) using multiple reaction monitoring. The quantification was performed with external standards. The recoveries of 5-methylmorpholino -3-amino-2oxazolidenone ( AMOZ ) , 3-Amino-2-oxazolidin -one(AOZ), semicarbazide(SC)and 1-amino-hydantoin(AHD) were in the range of 72.51-87.94% with spiked levels of 0.5-2.0μg/kg. The RSD were less than 5%. The limits of detection were 0.01μg/kg for AMOZ,0.02μg/kg for AOZ and 0.04μg/kg for SCA and AHD. (2)LC-ESI-MS was compared with LC-ESI-MS/MS. Detection limit of LC-ESI-MS method is 0.2μg/kg for RAC and 0.5μg/kg for CL, with low sensitivity, while detection limit of LC-ESI-MS/MS is 0.015μg/kg and 0.010μg/kg, with high sensitivity, can improve greatly stability,accuracy,reproducibility and detection limit. LC conditions and MS parameters are optimized, RSD is3.63-5.92%.(3)Same chromatography conditions can be taken when determining materials of these two groups .